Power storage device

Abstract

To provide a power storage device that can keep the sealability of a multilayer type battery even if a thermal impact is applied.SOLUTION: A power storage device includes a power storage device, and an exterior body that accommodates a power storage module. The power storage module includes a multilayer body electrode, a main surface, and a peripheral surface extending in a stacking direction. The main surface includes a plurality of first corner parts, and a plurality of side parts each held between two of the first corner parts. The peripheral surface includes a plurality of end surfaces that are continuous in a peripheral direction of the power storage module. Each end surface includes a plurality of second corner parts connecting to the different first corner parts respectively. The exterior body includes a laminate sheet including a metal layer, and a plurality of protective sheets each welded to the laminate sheet. The laminate sheet includes a main wall part covering each first corner part and each side part, and a peripheral wall part covering each end surface. The respective protective sheets are provided at positions corresponding to the first corner parts and a plurality of second corner parts each connecting to the first corner part in a border region between the main wall part and the peripheral wall part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a power storage device.

Background Art

[0002] Conventionally, various power storage devices have been known. Japanese Patent Application Laid-Open No. 2004-134210 (Patent Document 1) discloses a bipolar laminated battery as an example of a power storage device. In the laminated battery, sheet-like electrodes are laminated with an electrolyte layer interposed therebetween. In the laminated battery, the electrodes are laminated on the outermost layer so that the current collectors contained in the electrodes are exposed to the outside of the battery in the stacking direction of the electrodes and function as terminals.

[0003] Specifically, a laminated sheet having an opening provided in the center is placed on each current collector of the two outermost electrodes. The four sides of each laminated sheet are sealed, and further, the edges of the openings of each laminated sheet are attached to the current collector with a sealing resin, whereby the four sides of the bipolar electrode and the electrolyte layer are sealed under reduced pressure. As each laminated sheet, a polymer-metal composite film in which a heat-sealable resin film, a metal foil, and a rigid resin film are laminated in this order is used.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, since a plurality of electrodes are sandwiched in the stacking direction by each laminated sheet, each laminated sheet is pre-drawn. By the drawing process, each laminated sheet is bent in the direction of the other laminated sheet near the peripheral portion of the two outermost electrodes.

[0006] When a thermal shock is applied to such a laminated battery due to a rapid temperature change, the metal foil of the laminate sheet may be torn at the bent portions as described above. If the metal foil is torn, the sealing property of the laminated battery by the laminate sheet is lost.

[0007] Therefore, the present disclosure provides a power storage device capable of maintaining the sealing property of a laminated battery even when a thermal shock is applied.

Means for Solving the Problems

[0008] According to an aspect of the present disclosure, a power storage device includes a power storage module having a laminated electrode body in which a plurality of electrodes are laminated in a predetermined direction, and an exterior body that houses the power storage module. The power storage module includes a main surface having a predetermined direction as a normal direction, and a peripheral surface extending in a predetermined direction from the main surface. The main surface has a plurality of first corner portions and a plurality of side portions each sandwiched between two first corner portions. The peripheral surface has a plurality of end surfaces continuous in the circumferential direction of the power storage module. Each end surface has a plurality of second corner portions each connected to a different first corner portion. The exterior body includes a laminate sheet having a metal layer, and a plurality of protective sheets each welded to the laminate sheet. The laminate sheet has a main wall portion covering each first corner portion and each side portion, and a peripheral wall portion covering each end surface. Each protective sheet is provided at a position corresponding to the first corner portion and a plurality of second corner portions each connected to the first corner portion in a boundary region between the main wall portion and the peripheral wall portion.

[0009] According to such a configuration, in the boundary region between the main wall portion and the peripheral wall portion, the protective sheet is located at the corner positions corresponding to the first corner portion and the plurality of second corner portions each connected to the first corner portion. Therefore, even if a crack occurs in the metal layer of the laminate sheet due to a thermal shock, the sealing property at the corner position can be ensured. Therefore, even when a thermal shock is applied to the power storage device, the sealing property of the power storage device can be maintained.

[0010] Preferably, each protective sheet is a resin barrier film that is more resistant to thermal shock than the metal layer and is covered with the laminate sheet.

[0011] According to such a configuration, it is possible to prevent the electrolytic solution injected into the power storage module from entering the laminate.

Effects of the Invention

[0012] According to the present disclosure, it is possible to maintain the sealing property of the laminated battery even when a thermal shock is applied.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments shown below, the same or common parts are denoted by the same reference numerals in the drawings, and the description thereof will not be repeated.

[0015] Hereinafter, as an example of the power storage device, a laminated battery will be described as an example. The laminated battery is mounted on an electric vehicle such as a hybrid vehicle capable of traveling using the power of at least one of a motor and an engine, or an electric vehicle that travels with a driving force obtained by electric energy.

[0016] Furthermore, hereinafter, the stacking direction of the electrodes in the laminated battery is also referred to as the "DR3 direction". The direction perpendicular to the stacking direction and the short side direction of the laminated battery are also referred to as the "DR1 direction". The direction perpendicular to the stacking direction and the long side direction of the laminated battery are also referred to as the "DR2 direction". The DR1 direction, the DR2 direction, and the DR3 direction are perpendicular to each other.

[0017] FIG. 1 is a perspective view of a laminated battery according to the present embodiment. FIG. 2 is a cross-sectional view taken along line II-II shown in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III shown in FIG. 1. With reference to FIGS. 1 to 3, the laminated battery 100 according to the present embodiment will be described.

[0018] As shown in FIGS. 1 to 3, the laminated battery 100 includes a power storage module 1 having a laminated electrode body 10 in which a plurality of electrodes (electrode plates 11) described later are laminated in the stacking direction and a resin sealing body 40, a structure 60 (FIG. 3), and an exterior body 20 that houses the power storage module 1 and the structure 60.

[0019] The power storage module 1 further has a first main surface 91, a second main surface 92 opposite to the first main surface 91, and a peripheral surface 93. The first main surface 91 and the second main surface 92 are end surfaces in the DR3 direction. The first main surface 91 and the second main surface 92 are parallel. The first main surface 91 and the second main surface 92 are surfaces that extend in the DR1 direction and the DR2 direction. The first main surface 91 is a surface that contacts a first conductive plate 18 described later. The second main surface 92 is a surface that contacts a second conductive plate 19 described later.

[0020] The circumferential surface 93 is a surface perpendicular to the first main surface 91 and the second main surface 92. In this example, the circumferential surface 93 is composed of four end surfaces 93a to 93d (see FIGS. 2, 3, and 7). Each of the end surfaces 93a to 93d is a side surface of the resin sealing body 40. In this example, each of the end surfaces 93a to 93d is a rectangular flat surface.

[0021] The exterior body 20 is electrically connected to the terminal electrodes of the stacked electrode body 10 described later and is provided so as to be able to extract current to the outside from the stacking direction. The exterior body 20 includes a first conductive plate 18, a second conductive plate 19, a first laminate sheet portion 21, a second laminate sheet portion 22, a resin sheet 50, and eight protective sheets 80. The laminated battery 100 is a secondary battery such as a lithium-ion battery, for example.

[0022] In FIG. 1, among the eight protective sheets 80, four protective sheets 80 on the side of the first laminate sheet portion 21 are illustrated. The remaining four protective sheets 80 are located on the side of the second laminate sheet portion 22. The four protective sheets 80 on the side of the first laminate sheet portion 21 and the four protective sheets 80 on the side of the second laminate sheet portion 22 are in positions facing each other in the DR3 direction. The four protective sheets 80 on the side of the first laminate sheet portion 21 and the four protective sheets 80 on the side of the second laminate sheet portion 22 are located at eight corners (specifically, the inside of the corners) of the laminated battery 100.

[0023] The four protective sheets 80 on the side of the first laminate sheet portion 21 are covered by the second sheet 32 of the first laminate sheet portion 21 described later (state (G) in FIG. 8). The four protective sheets 80 of the second laminate sheet portion 22 are also covered from the outside by the second sheet 32 of the second laminate sheet portion 22.

[0024] The second sheet 32 of the first laminate sheet portion 21 has a main wall portion 251 and a peripheral wall portion 252. Similarly, the second sheet 32 of the second laminate sheet portion 22 also has a main wall portion 251 and a peripheral wall portion 252. The main wall portion 251 is parallel to the first main surface 91 of the power storage module 1. The peripheral wall portion 252 is parallel to the circumferential surface 93 of the power storage module 1.

[0025] The stacked electrode body 10 includes a plurality of electrode plates 11, a plurality of separators 15, a positive terminal electrode 16, and a negative terminal electrode 17. The plurality of electrode plates 11, the positive terminal electrode 16, and the negative terminal electrode 17 are stacked in the stacking direction (DR3 direction in FIGS. 2 and 3) via the separator 15.

[0026] The separator 15 is formed in a sheet shape. Examples of the separator 15 include a porous film made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP), a woven fabric or non-woven fabric made of polypropylene, methyl cellulose, or the like. The separator 15 may be reinforced with a vinylidene fluoride resin compound.

[0027] The plurality of electrode plates 11 are provided between the positive terminal electrode 16 and the negative terminal electrode 17. The electrode plate 11 is, for example, a bipolar electrode. The electrode plate 11 includes a current collector 12, a positive electrode layer 13, and a negative electrode layer 14.

[0028] The current collector 12 may contain at least one selected from the group consisting of, for example, aluminum (Al), stainless steel, nickel (Ni), chromium (Cr), platinum (Pt), niobium (Nb), iron (Fe), titanium (Ti), and zinc (Zn). Further, the current collector 12 may be one obtained by performing plating on the surface of a metal foil.

[0029] The current collector 12 has a first surface 12a located on one side in the stacking direction and a second surface 12b located on the other side in the stacking direction. The negative electrode layer 14 is provided on the first surface 12a. The positive electrode layer 13 is provided on the second surface 12b.

[0030] The positive terminal electrode 16 is located on one side in the stacking direction. The positive terminal electrode 16 includes the current collector 12 and the positive electrode layer 13. Specifically, in the positive terminal electrode 16, the negative electrode layer 14 and the positive electrode layer 13 are not provided on the first surface 12a of the current collector 12, and the positive electrode layer 13 is provided on the second surface 12b of the current collector 12. A first conductive plate 18 is disposed on the first surface 12a of the current collector 12 in the positive terminal electrode 16. Note that the central portion (excluding the peripheral portion) of the first surface 12a of the current collector 12 in the positive terminal electrode 16 constitutes a part of the first main surface 91. The first main surface 91 includes the central portion of the first surface 12a of the current collector 12 in the positive terminal electrode 16 and the upper surface of the resin sealing body 40.

[0031] The negative terminal electrode 17 is located on the other side in the stacking direction. The negative terminal electrode 17 includes the current collector 12 and the negative electrode layer 14. Specifically, in the negative terminal electrode 17, the negative electrode layer 14 is provided on the first surface 12a of the current collector 12, and the negative electrode layer 14 and the positive electrode layer 13 are not provided on the second surface 12b of the current collector 12. A second conductive plate 19 is disposed on the second surface 12b of the current collector 12 in the negative terminal electrode 17. Note that the central portion (excluding the peripheral portion) of the second surface 12b of the current collector 12 in the negative terminal electrode 17 constitutes a part of the second main surface 92. The second main surface 92 includes the central portion of the second surface 12b of the current collector 12 in the negative terminal electrode 17 and the lower surface of the resin sealing body 40.

[0032] The positive electrode layer 13 is formed by coating a positive electrode active material on the second surface 12b. As the positive electrode active material, for example, those capable of occluding and releasing charge carriers such as lithium ions can be adopted. Specifically, as the positive electrode active material, those usable as the positive electrode active material of a lithium ion secondary battery, such as a lithium ion composite metal oxide having a layered rock salt structure, a metal oxide having a spinel structure, and a polyanion-based compound, can be adopted. Also, two or more positive electrode active materials may be used in combination. For example, the positive electrode active material may contain olivine-type lithium iron phosphate (LiFePO4).

[0033] The negative electrode layer 14 is formed by applying a negative electrode active material to the first surface 12a. As the negative electrode active material, for example, lithium, carbon, a metal compound, an element alloyable with lithium, or a compound thereof can be employed.

[0034] Note that in any of the plurality of electrode plates 11, the negative electrode terminal electrode 17, and the positive electrode terminal electrode 16, the peripheral portion of the current collector 12 is an uncoated region where the positive electrode layer 13 and the negative electrode layer 14 are not provided.

[0035] The resin sealing body 40 is provided so as to seal the periphery of the laminated electrode body 10. Specifically, the resin sealing body 40 seals the cell space formed between two adjacent electrode plates 11. An electrolytic solution is injected into the cell space. That is, the electrolytic solution is injected into the power storage module 1. The resin sealing body 40 is formed by curing a resin member such as a hot melt member, a thermoplastic resin, a thermosetting resin, or a photocurable resin. The resin sealing body 40 is provided in the above-described uncoated region.

[0036] The first conductive plate 18 and the second conductive plate 19 are provided so as to sandwich the laminated electrode body 10 in the stacking direction. Specifically, the first conductive plate 18 is disposed on the first surface 12a of the current collector 12 included in the positive electrode terminal electrode 16. That is, the first conductive plate 18 is disposed on the first main surface 91 of the current collector 12 included in the positive electrode terminal electrode 16. The first conductive plate 18 is electrically connected to the positive electrode terminal electrode 16 by being disposed in contact with the first surface 12a. The first conductive plate 18 functions as a positive electrode terminal of the laminated battery 100 by being electrically connected to the positive electrode terminal electrode 16.

[0037] The second conductive plate 19 is disposed on the second surface 12b of the current collector 12 included in the negative terminal electrode 17. That is, the second conductive plate 19 is disposed on the second major surface 92 of the current collector 12 included in the negative terminal electrode 17. The second conductive plate 19 is electrically connected to the negative terminal electrode 17 by being disposed in contact with the second surface 12b. The second conductive plate 19 functions as a negative electrode terminal of the laminated battery 100 by being electrically connected to the negative terminal electrode 17.

[0038] In the laminated battery 100, it is possible to draw out the current to the outside from the power storage module 1 accommodated inside through the first conductive plate 18 functioning as a positive electrode terminal and the second conductive plate 19 functioning as a negative electrode terminal without using a tab for drawing out the current to the outside.

[0039] The first conductive plate 18 and the second conductive plate 19 have a rectangular shape having a plurality of corners. The peripheries of the first conductive plate 18 and the second conductive plate 19 are located on the resin sealing body 40.

[0040] In this example, the first conductive plate 18 and the second conductive plate 19 are aluminum (Al) plates. However, the present invention is not limited to this, and the first conductive plate 18 and the second conductive plate 19 may contain at least one selected from the group consisting of aluminum (Al), stainless steel, nickel (Ni), chromium (Cr), platinum (Pt), niobium (Nb), iron (Fe), titanium (Ti), and zinc (Zn). Further, the current collector 12 may be obtained by plating the surface of a metal foil.

[0041] The first laminate sheet portion 21 is joined to the periphery of the first conductive plate 18. The first laminate sheet portion 21 is joined to the first conductive plate 18 with a resin sheet 50 interposed therebetween and the periphery of the first conductive plate 18. The second laminate sheet portion 22 is joined to the periphery of the second conductive plate 19. The second laminate sheet portion 22 is joined to the second conductive plate 19 with a resin sheet 50 interposed therebetween and the periphery of the second conductive plate 19.

[0042] In this example, the resin sheet 50 is formed of a resin material having insulating properties. The resin sheet 50 is formed of a resin material that can be welded to the first conductive plate 18 and the second conductive plate 19. In this example, the resin sheet 50 is a sealing film for insulation.

[0043] Specifically, the resin sheet 50 has resin layers 51, 52, and 53. The resin layer 51 is the inner layer. The resin layer 53 is the outer layer. The resin layer 52 is sandwiched between the resin layer 51 and the resin layer 53.

[0044] The resin layers 51 and 53 are sealing resin layers. As also shown in states (B) and (C) of FIG. 6 described later, the resin layers 51 and 53 are acid-modified (PPa) layers in this example. The resin layer 51 is thermally welded to the first conductive plate 18. The resin layer 52 is a layer of polypropylene (PP) in this example.

[0045] Note that the types of resins constituting the resin layers 51 to 53 are not limited to the above, and for example, heat-sealable resins such as polyethylene, polypropylene, modified polyethylene, and modified polypropylene can be appropriately employed.

[0046] The central portions of the first conductive plate 18 and the second conductive plate 19 are exposed regions that are not covered by the resin sheet 50, the first laminate sheet portion 21, and the second laminate sheet portion 22. Through the exposed regions, current can be directly taken out from the power storage module 1 housed inside to the outside.

[0047] The first laminate sheet portion 21 includes a plurality of first sheets 31 and a plurality of second sheets 32 (see FIGS. 2, 3, and 6). The plurality of first sheets 31 and the plurality of second sheets 32 cooperate to cover the periphery of the first conductive plate 18. The second laminate sheet portion 22 includes a plurality of first sheets 31 and a plurality of second sheets 32. The plurality of first sheets 31 and the plurality of second sheets 32 included in the second laminate sheet portion 22 cooperate to cover the periphery of the second conductive plate 19.

[0048] The first sheet 31 (see FIG. 2) has a first metal layer 310 and sealant resin layers 311 and 312. The first metal layer 310 has a sheet shape. In this example, as shown in state (E) of FIG. 6 described later, the first metal layer 310 is a layer of aluminum foil (Al foil). The first metal layer 310 is not limited to Al foil, and metal foils such as Ni foil, Cu foil, and stainless steel foil can also be used. The first metal layer 310 imparts moisture permeability resistance, air permeability resistance, and chemical resistance to the first sheet 31.

[0049] The sealant resin layers 311 and 312 are provided on both sides of the first metal layer 310. Specifically, the sealant resin layer 311 is provided on the inner surface of the first metal layer 310. The sealant resin layer 312 is provided on the outer surface of the first metal layer 310.

[0050] The sealant resin layers 311 and 312 are compatible with the resin sheet 50. In this example, the sealant resin layers 311 and 312 employ polypropylene (PP), but are not limited thereto. For example, heat-sealable resins such as polyethylene, polypropylene, modified polyethylene, and modified polypropylene may be employed for the sealant resin layers 311 and 312.

[0051] The sealant resin layers 311 and 312 function as a seal layer of the exterior body 20. Further, the sealant resin layers 311 and 312 also have a function as an insulating layer, and insulate the first laminate sheet portion 21 and the second laminate sheet portion 22 when the first laminate sheet portion 21 and the second laminate sheet portion 22 are joined.

[0052] The second sheet 32 (see FIG. 3) has a second metal layer 320, a first resin layer 321, a second resin layer 322, a third resin layer 323, and a fourth resin layer 324. In the second sheet 32, the third resin layer 323, the first resin layer 321, the second metal layer 320, the second resin layer 322, and the fourth resin layer 324 are laminated in this order from the inside to the outside of the laminated battery 100. The fourth resin layer 324 is the outermost layer in the second sheet 32.

[0053] In this example, as also shown in the state (F) of FIG. 6 described later, the second metal layer 320 is a layer of Al foil. The first resin layer 321 is a layer of acid-modified (PPa). The second resin layer 322 is a layer of nylon. The third resin layer 323 is a layer of polypropylene (PP). The outermost fourth resin layer 324 is a layer of polyethylene terephthalate (PET). The first resin layer 321 is provided on the first main surface 320a. The second resin layer 322 is provided on the second main surface 320b.

[0054] The second metal layer 320 has a sheet shape. The second metal layer 320 has a first main surface 320a and a second main surface 320b. The first main surface 320a is a surface facing the inner side (the side where the laminated electrode body 10 is located), and the second main surface 320b is a surface facing the outer side (the side opposite to the side where the laminated electrode body 10 is located).

[0055] The second metal layer 320 is not limited to Al foil, and metal foils such as Ni foil, Cu foil, and stainless steel foil can be used. The thickness of the second metal layer 320 may be thicker than the thickness of the first metal layer 310. The thickness of the second metal layer 320 and the thickness of the first metal layer 310 may be the same.

[0056] The third resin layer 323 is compatible with the sealant resin layer 312. As the third resin layer 323, in addition to polypropylene (PP), for example, heat-sealable resins such as polyethylene, modified polyethylene, and modified polypropylene can also be employed. For the fourth resin layer 324, a resin material that is incompatible with the sealant resin layer 312 may be used.

[0057] In the second sheet 32, a nylon layer (second resin layer 322) and a polyethylene terephthalate layer (fourth resin layer 324) are stacked outside the second metal layer 320. Therefore, the combination of the layers outside the second metal layer 320 has higher strength than the combination of the two layers (first resin layer 321 and third resin layer 323) inside the second metal layer 320 in the second sheet 32. Note that "higher strength" means high rigidity or tensile strength. This can preferably prevent the second metal layer 320 from being damaged when the second sheet 32 receives an external force such as being pierced.

[0058] By the way, as described above, the sealant resin layer 312 of the first sheet 31 (see FIG. 2) is a layer of polypropylene (PP). Therefore, the combination of the layers outside the second metal layer 320 of the second sheet 32 has higher strength than the sealant resin layer 312 of the first sheet 31. Therefore, the combination of the layers outside the second metal layer 320 in the second sheet 32 has higher strength than the sealant resin layer 312 of the first sheet 31. By increasing the strength of the second sheet 32, it is possible to preferably prevent the second sheet 32 from being damaged during the deep drawing forming described later.

[0059] The first laminated sheet portion 21 is formed by deep drawing in a state of being joined to the first conductive plate 18. That is, drawing processing is performed on the first laminated sheet portion 21. As a result, the first laminated sheet portion 21 has a shape that opens upward and downward. A flange portion 21f bent outward is provided at the lower opening end of the first laminated sheet portion 21.

[0060] The second laminated sheet portion 22 is formed by deep drawing in a state of being joined to the second conductive plate 19. That is, drawing processing is also performed on the second laminated sheet portion 22 in the same manner as the first laminated sheet portion 21. As a result, the second laminated sheet portion 22 has a shape that opens upward and downward. A flange portion 22f bent outward is provided at the upper opening end of the second laminated sheet portion 22.

[0061] The first laminate sheet portion 21 and the second laminate sheet portion 22 are provided with accommodation recesses 21c and 22c for accommodating the power storage module 1 therein. By the accommodation recesses 21c and 22c, a part of the first main surface 91, a part of the second main surface 92, and the peripheral surface 93 of the power storage module 1 are covered.

[0062] Specifically, by the accommodation recesses 21c and 22c, the peripheral edges of the upper surface and the lower surface of the power storage module 1, and the peripheral surface of the power storage module 1 are covered. Specifically, by the accommodation recesses 21c and 22c, the peripheral edges of the upper surface and the lower surface of the laminated electrode body 10, and the peripheral surface of the laminated electrode body 10 are covered. The central portion of the upper surface of the laminated electrode body 10 is covered by the first conductive plate 18. The central portion of the lower surface of the laminated electrode body 10 is covered by the second conductive plate 19.

[0063] The accommodation recesses 21c and 22c are constituted by, for example, portions formed by subjecting the first laminate sheet portion 21 and the second laminate sheet portion 22 to the above-described drawing process. Note that the accommodation recesses 21c and 22c are not limited to such portions, and may be provided as long as they can accommodate the laminated electrode body 10. Further, in the above description, the case where accommodation recesses are provided in both the first laminate sheet portion 21 and the second laminate sheet portion 22 is exemplified, but the accommodation recess may be provided only in one of the first laminate sheet portion 21 and the second laminate sheet portion 22.

[0064] The first sheet 31 has an inner end portion 31i located on the central side of the laminated electrode body 10. The second sheet 32 has an inner end portion 32i located on the central side of the laminated electrode body 10. The resin sheet 50 has an inner edge portion 50i and an outer edge portion 50c located on the central side of the laminated electrode body 10.

[0065] In order to ensure the insulation distance between the first metal layer 310 of the first sheet 31 and the second metal layer 320 of the second sheet 32, and the first conductive plate 18 and the second conductive plate 19, the inner edge portion 50i is located closer to the center of the laminated electrode body 10 than the inner ends 31i, 32i.

[0066] The first conductive plate 18 has an outer edge portion 18c. The second conductive plate 19 has an outer edge portion 19c. The inner ends 31i, 32i are located closer to the center of the laminated electrode body 10 than the outer edge portions 18c, 19c.

[0067] The portions where the first conductive plate 18 and the second conductive plate 19 overlap with the resin sheet 50 are welded. The joint interface of the overlapping portions is sealed.

[0068] The outer edge portion 50c of the resin sheet 50 is located outside the outer edge portions 18c, 19c, but is not limited thereto, and the outer edge portion 50c and the outer edge portions 18c, 19c may be flush.

[0069] By joining the first sheet 31 and the second sheet 32 to the first conductive plate 18 and the second conductive plate 19 via the resin sheet 50, short - circuiting between the first conductive plate 18 and the second conductive plate 19 through the first sheet 31 having the first metal layer 310 or the second sheet 32 having the second metal layer 320 is suppressed.

[0070] Next, the structure 60 will be described. As described above, the structure 60 is housed in the exterior body 20. As shown in FIG. 3, the structure 60 is arranged in a state of facing the peripheral surface 93 (specifically, the end surfaces 93a, 93c) of the power storage module 1.

[0071] FIG. 4 is a perspective view of the structure 60. As shown in FIG. 4, the structure 60 is box - shaped in this example. The structure 60 is typically formed of resin. The structure 60 includes a base portion 61 extending in the DR3 direction in a side view of the power storage module 1 (see FIG. 3).

[0072] The structure 60 further includes two wall portions 62 and 64 that extend from the base portion 61 in the DR2 direction parallel to the first main surface 91 of the power storage module 1 and toward the circumferential surface 93. The structure 60 further includes two wall portions 63 and 65 that extend from the base portion 61 in the DR2 direction perpendicular to the first main surface 91 and toward the circumferential surface 93.

[0073] Each of the wall portions 62, 63, 64, and 65 rising from the base portion 61 is continuous in this order. The wall portion 62 is located on the side of the first conductive plate 18. The wall portion 64 is located on the side of the second conductive plate 19. The base portion 61 and the wall portions 62, 63, 64, and 65 form a rectangular parallelepiped-shaped space 690 having an opening.

[0074] The structure 60 has an outer surface 60s and an inner surface 60t on the circumferential surface 93 side of the outer surface 60s. The first and second laminate sheet portions 21 and 22 (see FIG. 1) constituting the exterior body 20 are arranged to cover the outer surface 60s of the structure 60. Specifically, each second sheet 32 (see FIG. 3) of the first and second laminate sheet portions 21 and 22 is arranged to cover the outer surface 60s of the structure 60.

[0075] Between the inner surface 60t of the portion of the base portion 61 in the structure 60 and the end face 93a of the power storage module 1, as shown in FIG. 3, a sealed internal space 800 is formed by each second sheet 32 of the first and second laminate sheet portions 21 and 22. The internal space 800 is depressurized to a negative pressure with respect to the atmospheric pressure (atmospheric pressure in this example) of the external space of the laminated battery 100. In this example, the internal space 800 is depressurized to about 1 kPa (kilopascal) in the initial state. The internal space 800 is in a low vacuum state by evacuation. The pressure difference between the internal space 800 of the laminated battery 100 and the external space generated by such depressurization applies a restraining force to the laminated electrode body 10.

[0076] As described above, the laminated battery 100, which is an example of a power storage device, includes a laminated electrode body 10 and a power storage module 1 having first and second main surfaces 91 and 92 and a peripheral surface 93 perpendicular to the first and second main surfaces 91 and 92. As shown in FIGS. 2 and 3, the laminated battery 100 further includes an exterior body 20 that houses the power storage module 1. As shown in FIGS. 3 and 4, the exterior body 20 has an outer surface 60s and an inner surface 60t on the side of the peripheral surface 93 rather than the outer surface 60s, and includes a structure 60 disposed in a state of facing the peripheral surface 93.

[0077] As shown in FIG. 3, the exterior body 20 further includes first and second laminate sheet portions 21 and 22 disposed so as to cover the outer surface 60s. As shown in FIG. 3, an internal space 800 sealed by the first and second laminate sheet portions 21 and 22 is formed between the inner surface 60t and the peripheral surface 93. The internal space 800 is depressurized so as to be in a negative pressure with respect to the atmospheric pressure of the external space of the laminated battery 100.

[0078] FIG. 5 is a perspective view of the power storage module 1. As shown in FIG. 5, the power storage module 1 includes a first main surface 91 and a peripheral surface 93. As described above, the power storage module 1 further includes a second main surface 92 (see FIGS. 2 and 3) on the side opposite to the first main surface 91. The peripheral surface 93 is composed of four rectangular end surfaces 93a to 93d. The directions of the normal lines of the first main surface 91 and the second main surface 92 are in the DR3 direction. The peripheral surface 93 extends in the DR3 direction from the first main surface 91 or the second main surface 92.

[0079] The first main surface 91 has a plurality of corner portions 911 and a plurality of side portions 912 each sandwiched between two corner portions 911. In this example, the first main surface 91 has four corner portions 911 and four side portions 912.

[0080] As described above, the peripheral surface 93 has a plurality of end faces 93a to 93d that are continuous in the circumferential direction of the power storage module 1. Each of the end faces 93a to 93d has a plurality of corner portions 921, each of which is connected to a different corner portion 911. In this example, the end faces 93a to 93d each have four corner portions 921. Of the four corner portions 921, the two corner portions 921 on the first main surface 91 side are each connected to a different corner portion 911 of the first main surface 91. Note that one corner portion 911 and the two corner portions 921 connected to the corner portion 911 (specifically, two consecutive corner portions 921 of different end faces) constitute one corner (specifically, a three-dimensional corner) of the power storage module 1.

[0081] Similar to the first main surface, the second main surface 92 also has four corner portions 911 and four side portions 912. Of the four corner portions 921 of the end faces 93a to 93d, the two corner portions 921 on the second main surface 92 side are each connected to a different corner portion 911 of the second main surface 92.

[0082] FIG. 6 is a cross-sectional view taken along line VI-VI shown in FIG. 1. As shown in FIG. 6, the first laminate sheet portion 21 has a second sheet 32 and a protective sheet 80. In the second sheet 32, as described above, from the inside to the outside of the laminated battery 100, a third resin layer 323, a first resin layer 321, a second metal layer 320, a second resin layer 322, and a fourth resin layer 324 are laminated in this order.

[0083] The protective sheet 80 is disposed between the corner portions 911 and the plurality of corner portions 921 connected to the corner portions 911 and the second sheet 32. The protective sheet 80 is a resin barrier film. The resin barrier film contains a resin having high gas barrier properties.

[0084] Resins containing vinyl alcohol such as EVOH and polyvinyl alcohol (PVA) as monomers show high gas barrier properties because the molecules can aggregate compactly. A resin barrier film formed by laminating such a gas barrier resin with a resin having low moisture permeability, such as PP or PE, used as a sealant resin, suppresses (barriers) the permeation of air and the electrolyte (gas) leaking through the resin seal part of the module. Such a resin barrier film is used as the protective sheet 80.

[0085] The protective sheet 80 is more resistant to thermal shock than the second metal layer 320. The protective sheet 80 has, from the inside to the outside of the laminated battery 100, a second resin layer 821, a first resin layer 820, and a third resin layer 822 in this order. The first resin layer 820 is a layer of an ethylene-vinyl alcohol copolymer resin (EVOH: Ethylene-Vinyl alcOHol copolymer). The second resin layer 821 and the third resin layer 822 are layers of polypropylene (PP).

[0086] The protective sheet 80 is welded to the second sheet 32. Specifically, the protective sheet 80 is welded to the third resin layer 323 of the second sheet 32. More specifically, the third resin layer 822 of the protective sheet 80 and the third resin layer 323 of the second sheet 32 are welded to each other.

[0087] The main wall portion 251 (see FIGS. 1 to 3) of the first laminate sheet portion 21 covers each corner portion 911 of the first main surface 91 and each side portion 912 of the first main surface 91. The peripheral wall portion 252 of the first laminate sheet portion 21 covers each end surface 93a to 93d. Similarly, the main wall portion 251 of the second laminate sheet portion 22 covers each corner portion 911 of the second main surface 92 and each side portion 912 of the second main surface 92. The peripheral wall portion 252 of the second laminate sheet portion 22 covers each end surface 93a to 93d.

[0088] Each protective sheet 80 is provided at positions corresponding to the corner portion 911 and two corner portions 921 each connected to the corner portion 911 in the boundary region R (see FIGS. 2 and 3) between the main wall portion 251 and the peripheral wall portion 252. Specifically, as an example, the corner portion 911 of the first main surface 91, the corner portion 921 of the end surface 93b of the peripheral surface 93, and the corner portion 921 of the end surface 93c of the peripheral surface 93 face the second resin layer 821 (the portion of the second resin layer 821 shown in FIG. 6) of the protective sheet 80.

[0089] From the above, focusing on the first main surface 91 among the first main surface 91 and the second main surface 92, the laminated battery 100 has the following configuration.

[0090] As shown in FIGS. 2 and 3, the laminated battery 100 includes a power storage module 1 having a laminated electrode body 10 in which a plurality of electrodes are laminated in the DR3 direction (lamination), and an exterior body 20 that houses the power storage module 1. The power storage module 1 includes a first main surface 91 having the DR3 direction as the normal direction, and a peripheral surface 93 extending in the DR3 direction from the first main surface 91.

[0091] As shown in FIG. 5, the first main surface 91 has a plurality of corner portions 911 and a plurality of side portions 912 each sandwiched between two corner portions 911. The peripheral surface 93 has a plurality of end surfaces 93a to 93d continuous in the circumferential direction of the power storage module 1. Each of the end surfaces 93a to 93d has a plurality of corner portions 921 each connected to a different corner portion 911.

[0092] As shown in FIGS. 1 and 6, the exterior body 20 includes a second sheet 32 having a second metal layer 320 and a plurality of protective sheets 80 each welded to the second sheet 32. The second sheet 32 has a main wall portion 251 that covers each corner portion 911 and each side portion 912 of the power storage module 1 shown in FIG. 5, and a peripheral wall portion 252 that covers each of the end surfaces 93a to 93d of the power storage module 1. Each protective sheet 80 is provided at positions corresponding to the corner portion 911 and a plurality of corner portions 921 each connected to the corner portion 911 in the boundary region R (FIGS. 2 and 3) between the main wall portion 251 and the peripheral wall portion 252.

[0093] FIG. 7 is a cross-sectional view taken along line VI-VI shown in FIG. 1 after a thermal shock is applied. As shown in FIG. 7, a crack 399 has occurred in the second metal layer 320 of the second sheet 32 due to the thermal shock. When the crack 399 occurs, the sealing property of the second sheet 32 is impaired.

[0094] Incidentally, among the boundary regions R (FIGS. 2 and 3) between the main wall portion 251 and the peripheral wall portion 252, positions corresponding to the corner portion 911 and a plurality of corner portions 921 each connected to the corner portion 911 (hereinafter, also referred to as "corner positions") are more likely to have cracks occur in the second metal layer 320 due to thermal shock than other positions. Therefore, as shown in FIGS. 6 and 7, by providing the protective sheet 80 at the corner position, the sealing property of the first laminate sheet portion 21 can be ensured even if the crack 399 occurs. Note that this also applies to the second laminate sheet portion 22. Thus, according to the laminated battery 100, it is possible to maintain the sealing property of the laminated battery 100 even when a thermal shock is applied.

[0095] Each protective sheet 80 is a resin barrier film that is more resistant to thermal shock than the second metal layer 320 and is covered by the second sheet 32. Therefore, it is possible to prevent the electrolytic solution injected into the power storage module 1 from entering the second sheet 32.

[0096] FIG. 8 is a diagram for explaining a method of manufacturing the first laminate sheet portion 21. As shown in state (A) of FIG. 6, an aluminum plate to be the first conductive plate 18 is prepared. As shown in state (B), two resin sheets 50 are welded along the two long sides of the aluminum plate. Next, as shown in state (C), two resin sheets 50 are welded along the two short sides of the aluminum plate. The resin sheets 50 on the long side and the resin sheets 50 on the short side overlap at the four corner portions shown in state (C).

[0097] As shown in state (D), two resin sheets 70 are welded to each of the two resin sheets 50 on the long side. In this example, each resin sheet 70 has the same layer structure as the resin sheet 50. The two resin sheets 70 on the right side of the figure are spaced apart from each other in the DR2 direction and extend in the D1 direction. Similarly, the two resin sheets 70 on the left side of the figure are also spaced apart from each other in the DR2 direction and extend in the D1 direction. The four resin sheets 70 are welded to the resin sheet 50 on the long side in a state of protruding from the resin sheet 50 in the direction opposite to the aluminum plate.

[0098] As shown in state (E), a protective sheet 80 is welded to each of the four corners of the intermediate body of the first laminate sheet portion 21 shown in state (D). Specifically, the protective sheet 80 is welded to both longitudinal ends of the two resin sheets 50 on the short side. That is, the protective sheet 80 is welded to the upper and lower resin sheets 50 in the figure. Four protective sheets 80 are welded to the resin sheet 50.

[0099] As shown in state (F), one first sheet 31 is welded to the resin sheet 50 and the two resin sheets 70 on the right side of the figure. Similarly, one first sheet 31 is also welded to the resin sheet 50 and the two resin sheets 70 on the left side of the figure. Each first sheet extends in the DR2 direction. Each first sheet is longer than the separation distance between the resin sheets 70 in the DR2 direction.

[0100] As shown in state (G), one second sheet 32 is welded to the upper resin sheet 50 in the figure, the two upper resin sheets 70 in the figure, the ends of the two first sheets 31 (the upper ends in the figure), and the two upper protective sheets 80 in the figure. The second sheet 32 is U-shaped. Similarly, one second sheet 32 is also welded to the lower resin sheet 50 in the figure, the two lower resin sheets 70 in the figure, the ends of the two first sheets 31 (the lower ends in the figure), and the two lower protective sheets 80 in the figure. The second sheets 32 are spaced apart from each other and are in a state of facing each other in the DR2 direction. Note that the intermediate body of the first laminate sheet portion 21 shown as state (G) is line-symmetric in each of the DR1 direction and the DR2 direction.

[0101] By performing a drawing process on the intermediate body along the virtual line L, as shown in state (H), the first laminate sheet portion 21 is generated. By the drawing process, the flange portion 21f of the first laminate sheet portion 21 is formed. In a top view of the intermediate body of the first laminate sheet portion 21 shown in state (G), the virtual line L overlaps with each protective sheet 80. Therefore, each protective sheet 80 is positioned inside (at the corner) of the corner of the first laminate sheet portion 21 as shown in state (H) and FIG. 1.

[0102] Note that the first laminate sheet portion 21 and the second laminate sheet portion 22 have the same shape. The second laminate sheet portion 22 is also manufactured in the same manner as the first laminate sheet portion 21. Therefore, the description of the manufacturing method of the second laminate sheet portion 22 will not be repeated here.

[0103] FIG. 9 is a diagram for explaining a method of manufacturing the laminated battery 100 using the power storage module 1, the structure 60, and the exterior body 20. As shown in states (A) and (B) of FIG. 9, the structure 60 is installed on one of the two short sides of the power storage module 1. The structure 60 is installed at a position facing the end face 93a that constitutes the peripheral surface 93 of the power storage module 1.

[0104] In this example, the laminated battery 100 further includes structures 60A and 60B. The structures 60A and 60B have the same structure and function as the structure 60. The structure 60A is shorter in length in the DR1 direction than the structure 60. The structure 60B is longer in length in the DR1 direction than the structure 60. The structures 60A and 60B are housed in the exterior body 20 in the same manner as the structure 60.

[0105] The structure 60A is installed on the same side as the structure 60. The structure 60A is installed such that the opening side faces the end face 93a, similar to the structure 60. The structure 60B is installed on the short side opposite to the structure 60. The structure 60B is installed at a position facing the end face 93c of the power storage module 1. Specifically, the structure 60B is installed such that the opening side faces the end face 93c.

[0106] As shown in state (C), the power storage module 1 and the three structures 60, 60A, and 60B are sandwiched between the first laminate sheet portion 21 and the second laminate sheet portion 22. Note that the second laminate sheet portion 22 is in a turned-back state. Thereafter, the first laminate sheet portion 21 and the second laminate sheet portion 22 are welded to each other, and the laminated battery 100 is completed as shown in state (D).

[0107] <Modification Example> In the above, as shown in state (G) of FIG. 8 and FIG. 1, the protective sheet 80 is provided inside the second sheet 32. However, it is not limited to this. The protective sheet 80 may be provided outside the second sheet 32.

[0108] The embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present disclosure is shown by the claims, and all modifications within the meaning and scope equivalent to the claims are included.

Description of Reference Numerals

[0109] 1 Battery module, 10 Stacked electrode body, 11 Electrode plate, 12 Current collector, 12a First surface, 12b Second surface, 13 Positive electrode layer, 14 Negative electrode layer, 15 Separator, 16 Positive electrode terminal electrode, 17 Negative electrode terminal electrode, 18 First conductive plate, 18c, 19c, 50c Outer edge portion, 19 Second conductive plate, 20 Exterior body, 21 First laminate sheet portion, 22 Second laminate sheet portion, 21c, 22c Accommodation recess, 21f, 22f Flange portion, 31 First sheet, 31i, 32i Inner end portion, 32 Second sheet, 40 Resin sealing body, 50, 70 Resin sheet, 50i Inner edge portion, 51, 52, 53 Resin layer, 60, 60A, 60B Structure, 60s Outer surface, 60t Inner surface, 61 Base portion, 62, 63, 64, 65 Wall portion, 80 Protection sheet, 91, 320a First main surface, 92, 320b Second main surface, 93 Peripheral surface, 93a, 93b, 93c, 93d End face, 100 Stacked battery, 251 Main wall portion, 252 Peripheral wall portion, 310 First metal layer, 311, 312 Sealant resin layer, 320 Second metal layer, 321, 820 First resin layer, 322, 821 Second resin layer, 323, 822 Third resin layer, 324 Fourth resin layer, 399 Crack, 800 Internal space, 911, 921 Corner portion, 912 Side portion, L Virtual line, R Boundary region.

Claims

1. A power storage module having a laminated electrode body in which a plurality of electrodes are laminated in a predetermined direction, and an exterior body that houses the power storage module, wherein the power storage module includes a main surface having the predetermined direction as a normal direction and a peripheral surface extending in the predetermined direction from the main surface, the main surface has a plurality of first corner portions and a plurality of side portions each sandwiched between two of the first corner portions, the peripheral surface has a plurality of end surfaces continuous in the circumferential direction of the power storage module, each of the end surfaces has a plurality of second corner portions each connected to a different one of the first corner portions, the exterior body includes a laminate sheet having a metal layer and a plurality of protective sheets each welded to the laminate sheet, the laminate sheet has a main wall portion covering each of the first corner portions and the side portions and a peripheral wall portion covering each of the end surfaces, each of the protective sheets is provided at a position corresponding to the first corner portion and the plurality of second corner portions each connected to the first corner portion in a boundary region between the main wall portion and the peripheral wall portion. A power storage device.

2. The power storage device according to claim 1, wherein each of the protective sheets is a resin barrier film that is more resistant to thermal shock than the metal layer and is covered with the laminate sheet.

Images